Which word suggests that a pesticide is the least toxic?

The term "Caution" is used to indicate that a pesticide is the least toxic among the classifications provided. In the context of pesticide labeling, different words are used to signify varying levels of toxicity.

When "Caution" appears on a pesticide label, it typically indicates that the product poses a lower risk to humans and the environment compared to products labeled with "Warning" or "Danger." "Caution" signifies that while the pesticide should still be handled carefully, it is generally considered to be safer for use.

"Warning" suggests a moderate level of toxicity, meaning the product is more dangerous than those labeled with "Caution." The terms "Danger" and "Hazardous" indicate a higher level of toxicity and risk, as they are used to label products that can cause severe health effects or pose significant dangers if mishandled. Thus, "Caution" is the correct choice, as it denotes a lower toxicity level compared to the other terms mentioned.